Month: August 2017

The theory of herd immunity goes something like this:

1. Vaccines produce antibodies, which are like guards that stay resident, ready to catch a particular villain if it tries to enter. This is called immunity;

2. Mass vaccination creates mass immunity, or herd immunity;

3. When the herd is immune, the disease has nowhere to go; it’s refused entry, everywhere; so it doesn’t hang around;

4. This herd immunity protects those who, for whatever reason, can’t be vaccinated.

Sounds like a good idea, doesn’t it? I don’t subscribe to it myself. But if you’re one of the majority that do, prepare to be disappointed by the study I’m about to discuss.

First, a bit of background. Intravenous immunoglogulin (IVIG) is manfactured from blood donations. It contains antibodies and is used to treat patients with immunodeficiency disorders – that is, those who can’t produce enough antibodies on their own.

But a problem has emerged recently in that the levels of measles antibody in donated blood have been declining over the years, and are now too low to reliably meet the requirements (at least those in the USA) for IVIG.

In a nutshell, the researchers pooled the donated blood into lots based on donor birth year. They then analysed the mean levels of measles antibody separately for those who, based on their birth year, would have received:

a) no vaccine;
b) a single dose of vaccine (either killed or live vaccine); or
c) two doses of live vaccine.

According to the findings, the unvaccinated cohort were brimming with immunity. They had three times the level of antibodies as the single dose group, and eight times that of the double dose group!

The reason there’s been a slow overall decline is that, as the unvaccinated population ages, it is gradually replaced by a doubly-vaccinated population that has almost no antibody.